Process for the polymerization of alpha-olefins

ABSTRACT

POLYMERIZATION OF A-OLEFINS IS CARRIED OUT IN THE PRESENCE OF A SOLID CATALYST WHICH IS COMPOSED OF AN ORGANIC COMPOUND OF A METAL OF GROUPS I TO III OF THE PERIODIC TABLE AND A CRYSTALLINE HALIDE OF A REDUCED METAL OF GROUPS IVB, VB OR VIB OF THE PERIODIC TABLE DEPOSITED ON A PULVERULENT SUPPORT. THE REDUCED METAL HALIDE IS OBTAINED BY REDUCING A HALIDE OF THE METAL AT ITS MAXIMUM VALENCE WTH AN ORGANOMETALLIC COMPOUND AT A TEMPERATURE BELOW 0*C. AND IN THE ABSENCE OF LIQUID DILUENT WHEREIN THE HALIDE OF THE METAL AT ITS MAXIMUM VALENCE OR THE ORGANOMETALLIC COMPOUND HAS BEEN ABSORBED ON A SOLID PULVERULENT SUPPORT PRIOR TO THE REDUCTION. CATALYSTS PREPARED IN THIS MANNER HAVE A HIGH STEREOSPECIFICITY AND CATALYST ACTIVITY, AND POLYMERIZATION CARRIED OUT IN THE PRESENCE THEREOF YIELDS HIGHLY ISOTACTIC CRYSTALLINE POLYMER.

United States Patent Int. Cl. c0sr1/56, 3/10 US. Cl. 260-933 9 Claims ABSTRACT OF THE DISCLOSURE Polymerization of a-olefins is carried out in the presence of a solid catalyst which is composed of an organic compound of a metal of Groups I to III of the Periodic Table and a crystalline halide of a reduced metal of Groups IVb, Vb or VIb of the Periodic Table deposited on a pulverulent support. The reduced metal halide is obtained by reducing a halide of the metal at its maximum valence with an organornetallic compound at a temperature below 0 C. and in the absence of liquid diluent wherein the halide of the metal at its maximum valence or the organornetallic compound has been absorbed on a solid pulverulent support prior to the reduction. Catalysts prepared in this manner have a high stereospecificity and catalytic activity, and polymerization carried out in the presence thereof yields highly isotactic crystalline polymer.

This is a division of our copending US. patent application, Ser. No. 756,330, filed Aug. 29, 1968, which has issued on July 20, 1971 as US. Pat. No. 3,594,330.

BACKGROUND OF THE INVENTION This invention is directed to a process for the stereospecific polymerization of a-olefins in the presence of improved solid catalysts.

According to the prior art, the stereospecific polymerization of a-olefins, such as propylene, to form crystalline polymers having large contents of isotactic units is carried out very easily in the presence of Ziegler type catalysts, in which the inorganic component is a violet variety of crystalline titanium trichloride.

Violet TiCl is manufactured by reducing TiCl under appropriate conditions, by means of various reactive agents such as hydrogen, metallic aluminum or an organic derivative of aluminum. The relatively critical conditions under which TiCl -a is prepared are such that the product is very expensive.

On the other hand, up to the present time, the preparation of stereospecific catalysts directly from TiCl with the formation of violet TiCl either in situ or immediately before the polymerization, has required a series of delicate manipulations which are difficult to realize on an industrial basis.

Furthermore, the catalytic activity of stereospecific catalysts prepared from violet TiCl is not particularly high. As a consequence, the cost of this part of the catalyst contributes substantially to increase the cost of the preparation of the polyolefin. In addition, polyolefin prepared in this manner requires considerable purification in order to eliminate the important TiCl catalyst residues contained therein.

It is therefore particularly desirable to find a stereospecific catalyst which is not expensive and which has a very high catalytic activity.

High catalytic activity should be attained in particular by depositing violet TiCl on a solid having a large sur- 3,701,766 Patented Oct. 31, 1972 "ice face, in order to obtain a stereospecific catalyst having a large active area.

However, all the efforts which have been made up to now in depositing TiCl on a solid have not been rewarded due to the difiiculty of realizing a suitable deposit of violet TiCl on a support without losing either its activity or its stereospecificity. It should be noted that violet TiCl is a crystalline solid which is practically insoluble in all the well known solvents. Therefore, it is believed that it would be impossible to impregnate a support with violet TiCl in contrast to what may be accomplished easily by using a liquid or a compound having high solubility.

Another possibility would be to impregnate the support with TiCl, and then to reduce the same into violet TiCl This method has been used already for the preparation of stereospecific catalysts mounted on a support, but it has only resulted in an additional complication caused by the already complex processes of reducing TiCl which is present on the support. In any case, this method which is disclosed in Belgian Pats. No. 603,090 of April 26, 1961 and No. 608,977 of Oct. 9, 1961 has resulted only in the production of catalysts having a reduced stereospecificity and/or activity.

SUMMARY OF THE INVENTION The object of the present invention is the provision of an improved method for polymerizing tit-polymers, particularly the stereospecific polymerization of a-polymers.

Another object of the present invention is the provision of a new highly active and stereospecific catalyst for the polymerization of a-olefins.

A further object of the present invention is to provide a simple and economical process for obtaining at low cost a catalyst for the polymerization of olefins, which is both very active and which has a noted stereospecificity.

According to the invention, a-olefins are polymerized in the presence of a solid catalyst comprising a combination of an organic compound of a metal of the Groups I to III of the Periodic Table and a reduced crystalline halide of a metal of the Groups IVb, Vb, or VII) of the Periodic Table, which is deposited on an inert porous solid support. The reduced halide is obtained by reducing, in the absence of any liquid diluent and at a temperature lower than 0 C., a halide of a metal of Groups IVb, Vb or VIb, the metal being at its maximum valence. The reducing agent is an organornetallic compound which is identical to or different from the above component of the polymerization catalyst. Prior to the reduction, one of the reactants, i.e. either the halide of a metal at its maximum valence or the organornetallic compounds, is absorbed on a solid pulverulent support material and the reduction is carried out by combining the unabsorbed reactant with the support which has been impregnated with the other reactant. The quantities of solid support, of metal halide wherein the metal is at its maximum valence and of the organornetallic compound are chosen so that the reaction mixture remains pulverulent.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The supports which are used to carry out the process according to the invention should be inert towards the reactants utilized for the preparation of the catalysts, and for the polymerization. They should be free of active groups such as hydroxyl groups, which can react with the halides of the transition metals or with the organic derivatives of aluminum. If such active groups are present, they should be in sufiiciently low quantity with respect to the other reactants, that they do not consume an important portion thereof.

Since the reduction is carried out in such a manner that the reaction mixture always remains pulverulent, it

is advantageous to use a porous support. In this case, the reaction can be carried out within the pores of the support. Therefore, it is important that these pores have a volume sutficiently large to enable the support to absorb completely at least one of the above reactants, and preferably the two reactants used in the reduction process.

The following are particularly interesting supports for the preparation of stereospecific catalysts: alumina and in particular a-alumina or corundum, silica, aluminum silicates such as the. catalyst supports called silica-alumina and the kaolins, the magnesium silicates, magnesia, titaniumoxide, calcium carbonate, etc. Polyolefins themselves are particularly suitable provided they are sufliciently porous. For example, it has been found that polyethylene and polypropylene may be used successfully.

When a polyolefin which is identical to the one for-med during the polymerization is .used as the support, it has the particular advantage of preventing all contamination of the polyolefin by the catalyst support.

The maximum valence metal halides, wherein the metal is selected from those in Groups IVb, Vb or VIb which are to be reduced, should be in a liquid form, as is normal for practically .all the compounds of this class. Titanium tetrachloride and vanadium tetrachloride are preferred metal halides.

An organic compound of a metal of the Groups I to III of the Periodic Table, preferably an organometallic derivative of aluminum, may be used as reducing agent. The reducing agent may be selected from the group consisting of trialkylaluminum, dialkylaluminium halides, alkylaluminurn sesquihalides, monoalkylaluminum dihalides, alkylaluminum hydrides and the organometallic complexes containing two metals in Which one is aluminum, and. the compounds obtained by replacing the alkyl groups by cycloalkyl, aryl, arylalkyl or alkylaryl groups, in the above derivatives, wherein the replacing groups from 6 to 12 carbon atoms, such as tricyclohexylaluminum, diphenylaluminum chloride, tribenzylaluminum and tritolylaluminum'. Preferably, the alkylaluminum and alkylaluminum halides used as reducing agents in the present process are those in which the alkyl group contains from 1 to 12 carbon atoms, such as trimethylaluminum, triethylaluminum, triisobutylaluminum, diethylaluminum chloride, diethylaluminum iodide. Diisobutylaluminum chloride, di-n hexylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, n-butylaluminum dichloride, diisobutylaluminum hydride, di-n dodecylaluminum hydride and isobutylaluminum di hydride.

It is especially convenient to use lower-alkylaluminum,

lower-alkylaluminum halides, in particular diethylaluminum chloride, triethylaluminum and triisobutylaluminum.

The reduction is preceded by the step of absorbing the halide or the organometallic compound on the support.

Before being used, the supports should be dried very carefully, by heating at a temperature of 100 to 400 C. for a sufiicient period of time, or in the case of the supports which cannot withstand the above treatment, by a treatment undervacuum at a lower temperature.

The anhydrous support so obtained is thereafter contacted with any of the liquid reactants used in the reduction process, such as the halides of transition elements or the organometallic derivatives.

The absorption of the reactant within the pores of the support is generally carried out at room temperature, i.e. 18 to 25 C. However, the temperature is not critical, since the absorption may be carried out at a higher or lower temperature.

As in the case of all the reduction steps, the absorpttion is carried out in the absence of liquid diluent, by simply contacting the support with at least one of the pure liquid reactants.

The proportions of the reactant to be absorbed, and of the support to be used are chosen in such a manner 4 that the volume of the reactant is not higher than the total volume of the pores which could absorb the reactant. In practice, these proportions are adjusted so that the mixtures remains pulverulent.

The relative proportions of the reactant to be absorbed and of the support cannot be determined a priori from the physical properties of the support, for example from the volume of pores, as measured according to standard methods. To determine the maximum quantity of reactant which can be used, i.e. the volume of the pores open to this reactant, a practical test is employed which consists in measuring the maximum quantity of the particular reactant which can be absorbed by the support before it begins to be moist or sticky, or not pulberulent.

The reduction within the pores of the support is carried out at a temperature lower than 0 C. and preferably, a temperature of about C. to 0 C. may be used. The reaction is carried ,out advantageously at a temperature between 50" and l0 C. A temperature which is too high, particularly a temperature higher than about 0 C., leads to the formation of less active catalyst. On the other hand, too low a temperature even if it does not contribute to lower the activity of the stereospecificity of the catalyst, contributes to increasing the length of time required for the reduction.

During the reduction, the proportions of the two reactants should be such that the atomic ratio of the metal of the Groups I to III to the transition metal is lower or only slightly higher than 1. Thus, in the present process the atomic ratio of the metal (M) of Groups I to III to the transition metal (M i.e. M/M is in the range of, 0.3 to 15:1 and preferably about 0.5 to 12:1. Provisions are generally made so that the ratio of the number of alkyl groups to the number of atoms of the transition metal is between about 0.5 and 2, and most preferably between 0.9 and 1.5.

In general the two reactants are mixed progressively with one another. The easiest way is to add the liquid reactant dropwise to the granular support having absorbed thereon the other reactant. The addition is made while the mixture is agitated.

Since the reaction must be carried out at low temperature, at least one of the reactants should be cooled toa sufiiciently low temperature prior to the reaction. For example, the solid support may be cooled to a temperature lower than the reaction temperature while adding thereto the other reactant, which may or may not have been previously cooled.

The reduction is carried out under completely anhydrous conditions, in an atmosphere free of oxygen. For example, the reaction may be carried out by flushing the mixture with pure dry nitrogen.

After having completed the reduction or after having substantially completed the reaction, the solid catalyst which is insoluble in the solvent remains absorbed on the support In each case, the proportions of the reactants and the reducing conditions are so chosen that the reduction is as complete as possible in order to provide a catalyst with a maximum stereospecificity.

By measuring the distribution and the volumes of the pores on the untreated support and on the completely processed support which contains the reduced halide, it is possible to determine that the reduced halide is located within the pores of the support.

After having been formed on the support, the reduced halide may be submitted to a heat treatment to a temperature of 50 to 300 C., in order to increase its stereospecificity. However, it has been found that the above thermal treatment may nearly always be omitted since the catalyst as such already has a more than suflicient stereospecificity.

The stereospecific catalysts used in the process according to the invention are therefore obtained in a simple process by simply contacting various reactants in the absence of solvent. In the above process, there is The following examples are intended to illustrate the best mode contemplated for carrying out the present invention and must not be construed as limiting the scope of the invention in any manner whatsoever. Examples no Purification cycle of the Solvents 35 normally the designated by the letter R are not examples of the present ease; e catalyst Pe not e to be manlpjllated under invention, but rather are examples of catalysts not prevery delicate eondltlens, example, at high p pared according to the present invention and these examgf Ygl the heat treatment of the 3311111315t y be ples have been included for comparison purposes only.

ispense W1 The supported stereospecific catalyst according to the EXAMPLES 1 To 23 invention is 115;? for the polymerization of olefins in ac- (a) impregnation of the support cordance with own procedures. Generally, it should be activated by an organometallic compound of a metal of 2 f qgf gff gg f S s 4 g g i z Groups I to III of the Periodic Table, particularly an E a e ce 0 a organoaluminum compound such as trialkylaluminum or there f upder an atmoslihere of an alkylaluminum halide. Diethylaluminum chloride has the quantity Speclfied m the table which follows f been found to be a particularly efiicient activator since the support (med for at a tempeiamre of 110 it is a catalyst having maximum activity and stereo C. under a current of mtrogen. The flask is rotated and specificity pure TiCl is added in such a quantity that the product The stereospecific polymerization of a-olefins may be pulvemlent' h mlfxture homogemzed by carried out in accordance with any known procedures: tatmg the flask for a Perlod o 1 hour in the gaseous phase, in the absence of a liquid medium; (b) Reduction of T1C14 as a dispersion in an insert solvent, preferably a hydro- The flask is cooled down, while being continuously carbon; rotated at the temperature indicated, then there is added, as a dispersion in the monomer itself, which is liquid dropwise, a quantity of alkylaluminum to obtain the under 1ts pressure of saturation. desired Al/Ti atomic ratio. After having added the above The process according to the invention generally may quantity of alkylaluminum, the content of the flask which be used to polymerize any wolefins for example ethylene, remains pulverized is allowed to Warm up at room tempropylene, butene-l, pentene-l, methylbutene-l, hexene-l, Peramre' 3 methy1 and 4 methyl pentene l long chain ovolefins and In some cases, the solid so obtained is submitted to a styrene. It is particularly interesting for polymerizing proheat treatment at the mdlcated temperature pylene, butene-l and 4-methyl-pentene-1 and to produce (c) Polymerization highly isotactic crystalline polymers.

Because of the very high catalytic activity of the cat- 232 s fi f i gg zg 1: 5 gi gai igq alysts according to the invention, the polymerization proc- P W re 6 ess of the invention is simpler and often does not even 5 ml. of a 200 mg./ml. solution of Al(C H Cl; require a final purification of the polymer, a purification the specified quantity of the catalyst prepared as dewhich is always required and which is very complicated scribed in (b); when using the known catalyst prepared from violet tihydrogen under a partial pressure of 0.7 kg./cm. tanium trichloride. This is one of the main advantages of 1 liter of liquid propylene. the invention. Th

e temperature of the reaction medium 15 raised to It should also be noted that when using the above cat- 0 alysts, it is possible to exercise complete control of the 2 5 18 mamtamed therem for a Penod of 5 hours morphology of the polymer; there is a parallel between w S the morphology of the support and that of the polymen The excess propylene is removed and the polypropylene For example, when the support is formed with microrecovered spheres, there is obtained a polymer in the form of small e results of the pelymerllatlen tests eefl'lefl Out Wlth spheres in which the diameter is a function only of the e dlfiereflt ysts ccording to the embod1ments deproductivity. scribed hereinbelow are given in the followmg table:

TABLE 1 Preparation of catalyst Support Alkylaluminurn Quan- T1014 Specific ttty intro- Quan- Atomic surface, used, duced, tity, ratio Ex. No. Nature mJ/g. grams grams Nature grams Al/Ti }AlzO:1 c1o11S1rAdE11IrInsr1i3ct5%spIhe 4. 7 20. 8 7. l8 A1(C2H5)2Cl l 2. 79 0. 6

roi 21 o 4.7 15.3 10.5 AICH 01 4.05 0.6 eiii 4.7 26.6 9.17 41%02113201 3.52 0.6 fin 4.7 44.4 15.3 A1(C2H5)IC1 5.87 0.6 do 4.7 36.9 12.74 A1(C H3)2Cl 4.88 0.6 7 do 4.7 0.6 3.31 A1(CH5)Cl 1.27 0.6 118 Jan 4.7 17.8 6.11 A1(C,H )1Cl 2.34 0.6 R0 do 4.7 17.3 6.11 Al(CgH5)zCl 2.34 0.6 10 d0 4.7 13.16 3.4 4x04110011 2.4 1. 05 11-.- A110,, Ketjen) 220 22.0 15.2 muolfimoi 8.7 0. 62 12.-. ng g ggf ggfg 6.1 15.15 10.5 111 01H0101 4.02 0.6 13- KnolinVeline PA 12 13 16.84 2.9 111602110401 1.12 0.6 14 SiOa-MgO Davison 450 13.8 11.0 A1(1C4H0)2 l 6.88 0.62 15 rln 450 13.8 11.0 141601110101 6.88 0.62 16 MgO .p.a. (BDH)--. 23.2 14 26 4. 04 4x02110401 1.88 0.6 17 MgO easorb 43 59 15.4 5.35 111(01110101 2.03 0.6 10 J16 50 12.1 4.14 4x01130101 1.58 0.6 T101 rutile Cabot.-. 7.7 12.6 3.28 A1(C7H5)2Cl 1.25 0.6 10.75 3.1 AI(C2H6)2C1 1.19 0.6 15.37 5.3 A1 on1o4c1 2.02 0.6 15.2 10.36 Al(CzH5)zC1 3. 97 0.6 15.8 5. 52 AI(C2H5)2CI 2.1 0.6 Forming a hexane solution containing 56 g./l.; I Sticky solid at cold temperature which solidifies as a result of the addition of an excess of TiCli not absorbed within the pores of the support; I Prepared during a preceding test.

TABLE 2 EXAMPLE 24 Preparation of catalyst In a 30 l. autoclave, dried and flushed with a current Heat treatment Rate of of propylene, there are introduced: Reduc T1013 final tlon Tem- 1 Length content redue- 24 of Pure A1(c2H5)2 temperperaof otcattion, 5.1 g. of the catalyst used 1n Example 4, or 0.882 g. of Ex. ature, ture, Time, alyst, percent Shade of Ticl No. 0. 0 hours. mg./g. molecular catalyst 1782 V 1 Hydrogen under a p'artlal pressure of 0.5 leg/cmfi;

178 13;- gg fi 23 1. of liquid propylene. 166 58 Brownish violet. o 173 91 violet brown The temperature of the m1xture 1s raised to 60 C. 191 100 Violet. 174 92 Violet bmwm and 1s mamtained therem for a perlod of 30 hours while 177 93 Brown. stlrrmg.

2g 3- The excess of gaseous propylene is removed and 6.579 1 1 Do: kg. of polypropylene are recovered. The propylene hasa 3g? l g ggigfg g crystalllmty of as determined by differential thermal 104 92 Violet. an'alysls, and possesses an intrinsic viscosity of 3.7 d1./g. 33g g8 38- Durmg this test, the productivity is 1290 g. of poly- 171 89.5 violet brown. propylene per g. of the supported catalyst, the Ti content lg. g fi 9 of the resulting polypropylene is 41 p.p.m., which means 123 92 Violet. that no purlfication step 1s required.

137 72.4 Brownish violet. 232 84 Violet. EXALGPLE 25 161 8 -Into a 1.5 l. autoclave dried and flushed with a current 1 3 Tics-A1011 ('IiOl AA Sold by Staufier). 0f P py there are introduced:

1 The temperature could not be lowered below the given value because 25 61 1 teinderlcyl to sol ian an the catallystt hastgeeln preplrfiedfiig 11135 88 g. of bead polymerizatlon propylene, prepared durmg S0 1 8 an 373 B0 remalne pu V6111 en W1 9 res 3. 6 recovery thereoi is obviously limited and diflicult. the Precedmg test each P having a d1ameter between 1.4 and 2 mm. and having been dried under vacuum for a period of 2 hours at 80 C.;

TABLE 3 Polymerization Polymer obtained Crystal- Isotactic linity Catalytic character (by difier- Intrinsic Quantity activity, (insoluble ential viscosity of grams in boiling thermal at 140 0. catalyst P PP/hr., heptane), analysis), in tetused, obtained, grams percent percent ralin, dl mg. grams TiCl weight weight grams 273 161 142 97. 7 35. 2 1 13. 3 276 22 90 63.1 26. 9 1. 3 339 46 164 32. 7 41. 9 1. 6 331 167 585 81.6 37. 6 2. 9 364 130 385 91. 2 61 0.16 298 93 358 76. 6 41. 2 1. 9 419 94 263 73. 2 27. 1 4. 4 1,058 31 93 84. 2 39. 4 1. 7 9 21 71 78.7 35.5 1.6 1,028 119 194 92. s 31. 7 6. 4 488 162 226 71.7 93 2.0 469 258 449 71.0 37.3 4.3 499 169 664 86. 3 3s. 3 2. 7 336 126 234 86. 9 42. 6 1. 7 385 139 209 93.4 34. 3 1 11.1 339 326 455 78.0 as. a 1. 7 841 192 326 67. 6 26. 2 6. 6 460 64 162 67.3 24.6 1.3 900 363 661 34 4.3 696 186 364 76.6 37. 9 1. 6 960 387 696 71. 3 35. 3 1. 6 434 233 476 so 30.8 4.4 764 212 346 71.2 40. 3 1. 6

1 Test carried out in the absence of hydrogen.

NOTE.PP (polypropylene).

U pon comparing the examples carried out by using the 10 ml. of a solution of Al(C H Cl at a concentration of catalysts according to the invention with run R1 which 200 g- 1I1 heXaIle; is carried out by using one of the best Commercial 0.498 of the catalyst used in Example 6 hereinabove, catalysts, it is obvious that the improvements brought supported on microspheroidal alumina, for a total of about by the invention are mainly due to the activity, 87 mg. of TiCl t ta i character 0 the resultgggg g and he 180 ct c f The temperature of the reaction mixture 15 ralsed to A 7 comparison of runs R2 and R3 with Example 4 C. and 1s malntamed thereln for a period of 4 hours shows that only by using the process according to the wh1le st1rr1ng and prov1d1ng a partial pressure of gaseous invention is it possible to obtain catalysts having high p py fi 0f 10 f is g gi i gg combmed whwh easy 70 The excess gaseous propylene is removed and a total oprepare a 1 u menu of 1 o l n Runs R8 and R9 compared to Examples 4 to 7 and 18 g f g lShco1 lected ghlch 15 show a decrease of the activity, which can be observed Sieve so as 0 separae e ea 8 'avmg a 'ameter when the reduction is carried out at a higher tempera- Smaller than mmsaventy'seven P l/P py e ture..In practice, above 0 C. it isnot possible to obtain are ct d du lng he polymerizatlon test earned catalysts which are sufficiently active.. out in a gaseous phase.

9 The activity is 221 g. of polypropylene per hour and per g. of TiCl The crystallinity of the polypropylene so obtained, as determined by differential thermal analysis is 36.4% and the melting point is 161 C.

EXAMPLE 26 A catalyst containing 100 mg. of TiCl supported on kaolin Veline P A 12 (trademark), is prepared :by reducing at a temperature of 35 C., 2.9 g. of TiCl absorbed on 16.84 g. of Kaolin, by means of 1.12 g. of Al(C I-I Cl.

Into a 1.5 l. autoclave, previously dried and flushed with nitrogen, there are introduced successively:

5 ml. of a solution of Al(C H Cl having a concentration of 200 g./l.;

1.04 g. of the catalyst prepared as described above;

3 ml. of pure, dry 4-methylpentene-1;

hydrogen under a partial pressure of 0.1 kg./cm.

The mixture is heated at 60 C. while stirring and is maintained therein for hours and is cooled down. The resulting polymer is filtered and is dried under vacuum.

There are obtained 64 g. of poly-4-metylpentene-1 having a crystallinity of 18.5% measured by differential thermal analysis, a melting point of 239 C. and an intrinsic viscosity at 160 0., measured in Tetralin, of 3.7 dl./g.

The catalytic activity is 119 g./h.g. TiCl EXAMPLE 27 The polymerization of 750 ml. of butene-l is carried out at a temperature of 40 C. according to the process described above, under a partial pressure of 250 g./cm. of hydrogen.

By using 1.03 g. of a catalyst identical to the one described in Example 26, there are obtained 200 g. of polybutene, for a catalytic activity of 374 g./g. TiCl .h.

The polybutene was examined by dilferential thermal analysis and showed a crystallinity of 15.8% and a melting point of 114 C. The intrinsic viscosity measured at 115 C. in Decalin was 1.7 dL/g.

EXAMPLE 28 Into a 250 ml. flask, flushed with nitrogen, there were introduced 14.22 g. of corundum dried at 300 C. for 24 hours, and 1.88 g. of diethylaluminum chloride. The mixture is stirred for a period of 1 hour with a special stirrer adapted for stirring a powder.

The mixture is cooled down to 35 C. during 30 minutes then there are added dropwise, 4.9 g. of pure TiCL, in order that the atomic ratio Al/Ti becomes 0.6. At the end of the addition, the content of the flask is allowed to warm up at room temperature.

There is obtained a dark brown catalyst having a TiCl content of 175 mg./g. and a reducing rate of 92%.

Propylene is polymerized according to the method described in Examples 1 to 23 by means of 374 mg. of the above catalyst.

There are obtained 196 g. of polymer which corresponds to a catalytic activity of 600 g. of polypropylene per hour and per g. of TiCl The isotactic character of this product was 75.4% of insoluble matter in boiling heptane and the crystallinity was 36.7%. The intrinsic viscosity was 2.4 dl./g.

EXAMPLE 29 In the apparatus described for the preparation of the catalysts according to Examples 1 to 23, which has been flushed with dry nitrogen, there are introduced 17.72 g. of atomized kaolin Veline P A 12 (trademark), previously dried at 110 C. for a period of 19 hours, and 0.763 g. of pure Al(C H which mixture is stirred for a period of 0.5 hour.

The mixture is cooled down to 40 C. during a period of 30 minutes and there are added dropwise 3.02 g. of pure TiCl in order that the atomic ratio Al/Ti becomes 10 0.4. At the end of the addition, the content of the flask is allowed to warm up at room temperature.

There is obtained a dark brown catalyst having a TiCl content of 76 mg./ g. and a reducing rate of 66.6%.

Propylene is polymerized according to the process of Examples 1 to 23 by means of 123 mg. of the above catalyst.

There are obtained 337 g. of a polymer, which corresponds to a catalytic activity of 550 g. of polypropylene per hour and per g. of TiCl The crystallinity of the above product was 39.3%.

Although specific embodiments of the invention have just been described, it is understood that modifications are permissible, the scope of which is to be determined from the appended claims only.

What we claim as new and desire to secure by Letters Patent is:

1. In a method for polymerizing a-olefins in the presence of a solid catalyst comprised of a combination of an organic compound of a metal selected from a member of the group consisting of the elements of Groups I to III of the Periodic Table and a crystalline halide of a transition metal of Groups IVb, Vb and VIb of the Periodic Table in the reduced state deposited on a support, the improvement which comprises carrying out said polymerization in the presence of a catalyst obtained by reducing at a temperature lower than about 0 C. a reactant which is a halide of said transition metal at its maximum valence with a reactant which is an organometallic compound, the metal of said organometallic compound being selected from a member of the group consisting of the elements of Groups I to III of the Periodic Table, wherein the reduction is carried out in the absence of liquid diluent and one of said reactants in liquid form has been absorbed on a solid, porous, pulverulent support material prior to the reduction, the total volume of said absorbed reactant being not higher than the total volume of the pores of said solid support material and the second reactant in liquid form and said solid support material containing the absorbed reactant being combined slowly and under sufficient agitation to maintain the reaction mixture pulverulent.

2. Process according to claim 1 in which prior to the reduction, said halide of said transition metal at its maximum valence is absorbed on a solid pulverulent support and said still pulverulent support with the absorbed halide is cooled to a temperature lower than 0 C. and in which said reduction is then carried out by slowly adding said organometallic compound to said solid pulverulent support containing said absorbed halide of said metal.

3. Process according to claim 1 in which prior to the reduction said organometallic compound is absorbed on a solid pulverulent support and said still pulverulent support containing said organometallic compound is cooled to a temperature lower than 0 C. and in which said reduction is then carried out by slowly adding said halide of said metal at its maximum valence to said solid pulverulent support containing said organometallic compound.

4. Process according to claim 1 in which said halide of a metal of Groups IVb, Vb or VIb at its state of maximum valence is selected from the group consisting of titanium tetrachloride and vanadium tetrachloride.

5. Process according to claim 1 in which the organometallic compound used to reduce said metal halide is the same compound as the organic metal compound which forms the polymerization catalyst.

6. Process according to claim 1 in which the organometallic compound is selected from the group consisting of trialkylaluminum and alkylaluminum halide.

7. Process according to claim 1 in which the inert porous solid support is selected from the group consisting of alumina, silica, aluminum silicates, magnesium silicates, magnesia and titanium oxide.

8. Process according to claim 1 in which said solid support is a polyolefin.

1 1 9. Process according to claim 1 in which said solid support is a polyolefin identical to the polyolefin formed during the polymerization.

References Cited UNITED STATES PATENTS 3,047,551 7/1962 Thomas 260-88.2 3,058,963 10/1962 Vandenberg 26088.2

12 FOREIGN PATENTS 948,447 2/1964 Great Britain.

HARRY WONG, JR., Primary Examiner 5 E. J. SMITH, Assistant Examiner US. Cl. X.R.

260-93.5 S, 94.9 DA 

